German published patent application (OS) No. 2 124 024 shows a system for regulation or control of shift members of an automatic stepwise transmission of a motor vehicle in which a friction clutch between motor and the portion of the transmission that turns with the vehicle wheels has its engagement controlled with reference to a predetermined change of motor speed with respect to time. This predetermined amount of motor speed change is determined as a quantity that depends on the motor speed value, the motor torque, the direction of shift, the selection gear, the transmission oil temperature and the loading condition. The value of permissible jolt thus calculated and the actual value of jolt effect calculated by the time derivative of motor speed are supplied to a control circuit the output amplifier of which drives a mechanical control of a pressure controller for actuation of a friction clutch. The peak values of torque and of the oil pressure in the pressure control that occur during the shifting operation are diminished by the provision of delay devices, for example RC circuits in the electronic equipment or oil valves in the hydraulic equipment. A disadvantage of this known system is that the actual amount of jolt effect is only imperfectly determined, and the jolt that takes place after the engagement of the friction plates of the clutch, that is caused by the stiffness of the mechanical drive connection to the wheel, is not taken account of.
It is an object of the present invention to provide a more effective calculation of the potential jolt effect, so that the proper time for the engagement of a friction clutch in automatic or semiautomatic gear shifting can be more effectively determined without producing jolts not taken account of in the determination and without requiring the complication of delay and damping devices for smoothing jolt effects.